1. Field of the Invention
Embodiments of the present invention relate to systems and methods for controlling combustible fuel heating systems. More particularly, embodiments of the present invention relate to systems and methods for controlling gas flow to individual or multiple burners in a combustible fuel heating system.
2. Description of the Related Art
Residential and commercial gas furnace systems typically employ multiple burners to provide sufficient heating capacity. Generally, a combination control valve controls the supply of fuel from a fuel source to the burners in an on/off fashion, such that all the burners are either fully on or fully off. The furnace cannot turn on individual burners nor can it vary the flow of gas to the burners. This type of on/off control system often incurs temperature overshoot, wherein the output temperature (or the ambient temperature of the house or building) rises above the temperature setting as a result of all burners turning on at maximum capacity in an attempt to raise the temperature by a small amount. Thus, fine resolution control of the output temperature is difficult. Alternatively, if the control system is adjusted to reduce temperature overshoot, then there is often a large steady-state error of the output temperature as compared with the set temperature, typically on the cold side, as the control system waits until the output temperature drops low enough below the set temperature to turn on all the burners at maximum capacity. Therefore, the on/off heating control system is inefficient by using excessive energy to maintain the set temperature or is ineffective by leaving the burners off for too long resulting in a cold and uncomfortable environment.